“Farmers must get involved…”

23rd Mar 2022

A Welsh Vet shared with us a recent encounter that one of his clients had with Bovine Viral Diarrhoea (BVD) on his farm as a result of purchasing a Persistently Infected (PI) animal from a local market.

The farm in question bought 10 calves at a South Wales market at the beginning of November 2021 from multiple farms.

“As vets, we always recommend that all farms who buy animals should check for BVD with bloods or tags - and so blood samples were taken from these calves for BVD. Unfortunately, three out of the ten came back BVD antigen positive.”

The farm has 40 suckler cows and these bought-in calves were the source of future replacement cows. The farmer isolated the calves from the rest of the herd as soon as they came back from the market. The three calves who tested positive were kept isolated and were retested four weeks later. At the re-test, only one was still positive, a confirmed PI animal,  with the other two testing clear,  being transiently infected.

The farmer hadn’t checked the BVD status before buying. Informed purchase is always better and the welfare and financial consequences of BVD are much less likely if farmers buy from high health herds.

In this case, the farmer had bought what was on offer in the market that day and purchased what he thought were nice, healthy looking calves. A major way the virus spreads is by Persistently Infected (PI) cattle being present in herds. It can be easy to buy one in as they often don't present any symptoms at all.

“They had no symptoms initially but the whole bunch of calves did develop pneumonia and needed Zactran and Metacam treatment. Luckily as he had isolated them, it did not spread to the whole of the herd.”

This level of pneumonia was likely due to the immunosuppressive effects of BVD and a PI will challenge all animals it is in contact with in a herd with copious virus. PI animals act as a reservoir for the disease and will constantly spread the virus and could create more PI animals. PI animals cannot be treated or cured, they must be isolated and culled to stop the spread of BVD.

Care should be taken to minimize the risk of buying in further PI animals, through only buying in animals from BVD free herds.

“The infected animal was put down and hopefully no lasting damage was done to the herd. The farmer rang the market so they could contact the relevant vendor. I think in this day and age where there is plenty of awareness of BVD, the terms and conditions of the market should include forbidding selling a BVD PI animal. I also think that if you purchase a PI you should be able to ask for your money back.”

The vet stressed that all farmers must play their part to eradicate BVD;

“Especially with this year being the final year of free BVD screening through Gwaredu BVD, farmers must get involved.”

Here are some Gwaredu BVD tips on how you can minimize the risk of buying in PI and transiently infected animals:

  • Look out for our Gwaredu BVD certificates when buying stock to make informed purchasing decisions:

Bronze - Awarded to farms after one clear BVD antibody screen.
Silver - Awarded to farms that have screened BVD antibody clear for two consecutive years.
Gold - Awarded to farms that have screened BVD antibody clear for three or more consecutive years.

  • If buying from a farm with unknown BVD status or for extra security, isolate all brought in animals for three weeks to eliminate the risk of transient infection, and if needed test for BVD. 
  • If buying in-calf heifers from a market, isolate as above, but also remember to tag and test calves from these heifers after they are born.